109 prop pitch (rpm) and the supercharger

[Crumpp]

It's not just about maniaining the optimap pitch and engine RPM...

It is all about maintaining optimum pitch and rpm.

As you coarsen the pitch to reacquire the rpm, you will notice an increase in performance.

In the quoted cases, they are setting the engine to a limited over boost and coarsening the pitch to maintain rpm.

That is how it works.

The experienced pilots you are quoting are coarsening pitch before rpm drops. If you know the approximate performance for a given setting, then coarsening the pitch at rpm will cause an increase in performance within limits.
It will also cause a subsequent manifold pressure drop and the performance will suffer as a result if outside of a narrow range.